Segment Disclosures and Related Information - Sales (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
Sales and other operating revenues	$ 9,556	$ 2,749	$ 19,382	$ 8,907
Natural Gas [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	2,812	1,190	7,323	2,845
Natural Gas Liquids Reserves [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	325	84	562	235
Crude Oil [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	5,797	1,216	10,292	4,660
Other Products [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	622	259	1,205	1,167
U.S.
Segment Reporting Information [Line Items]
Sales and other operating revenues	7,308	1,844	15,015	6,061
Australia
Segment Reporting Information [Line Items]
Sales and other operating revenues	0	168	0	605
CA
Segment Reporting Information [Line Items]
Sales and other operating revenues	450	165	1,012	498
China
Segment Reporting Information [Line Items]
Sales and other operating revenues	171	67	326	213
Indonesia
Segment Reporting Information [Line Items]
Sales and other operating revenues	207	132	403	336
Libya
Segment Reporting Information [Line Items]
Sales and other operating revenues	290	0	520	44
Malaysia
Segment Reporting Information [Line Items]
Sales and other operating revenues	252	83	478	299
Norway
Segment Reporting Information [Line Items]
Sales and other operating revenues	618	242	1,030	688
United Kingdom
Segment Reporting Information [Line Items]
Sales and other operating revenues	257	46	593	156
Other foreign Countries
Segment Reporting Information [Line Items]
Sales and other operating revenues	3	2	5	7
Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	9,556	2,749	19,382	8,907
Alaska [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	1,418	419	2,551	1,532
Alaska [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	1,418	438	2,551	1,551
Alaska [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	0	19	0	19
Lower 48 [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	5,889	1,433	12,402	4,536
Lower 48 [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	5,887	1,405	12,398	4,498
Lower 48 [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	(2)	(28)	(4)	(38)
Canada [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	802	165	1,669	678
Canada [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	450	165	1,012	498
Canada [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	(352)	0	(657)	(180)
Europe, Middle East and North Africa [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	1,165	288	2,143	888
Asia Pacific [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	630	450	1,207	1,453
Other International [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	2	1	3	4
Corporate and Other [Member] \| Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	$ 4	$ 2	$ 68	$ 15